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enhance leader election doc

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This commit is contained in:
Andy Xie
2019-05-14 10:36:22 +08:00
parent 3706ef5254
commit 95f33ce399
1 changed files with 17 additions and 6 deletions
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23
staging/src/k8s.io/client-go/tools/leaderelection/leaderelection.go
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@@ -16,12 +16,15 @@ limitations under the License.
// Package leaderelection implements leader election of a set of endpoints. // Package leaderelection implements leader election of a set of endpoints.
// It uses an annotation in the endpoints object to store the record of the // It uses an annotation in the endpoints object to store the record of the
// election state. // election state. This implementation does not guarantee that only one
// client is acting as a leader (a.k.a. fencing).
// //
// This implementation does not guarantee that only one client is acting as a // A client observes timestamps captured locally to infer the state of the
// leader (a.k.a. fencing). A client observes timestamps captured locally to // leader election. Thus the implementation is tolerant to arbitrary clock
// infer the state of the leader election. Thus the implementation is tolerant // skew, but is not tolerant to arbitrary clock skew rate. Timestamp(renew time)
// to arbitrary clock skew, but is not tolerant to arbitrary clock skew rate. // is not meaningful if it was collected on another machine. The implementation
// of this client only acts on locally collected timestamps and cannot rely on
// the accuracy of timestamp in the record for correctness.
// //
// However the level of tolerance to skew rate can be configured by setting // However the level of tolerance to skew rate can be configured by setting
// RenewDeadline and LeaseDuration appropriately. The tolerance expressed as a // RenewDeadline and LeaseDuration appropriately. The tolerance expressed as a
@@ -104,7 +107,15 @@ type LeaderElectionConfig struct {
// LeaseDuration is the duration that non-leader candidates will // LeaseDuration is the duration that non-leader candidates will
// wait to force acquire leadership. This is measured against time of // wait to force acquire leadership. This is measured against time of
// last observed ack. // last observed ack. A client needs to wait a full LeaseDuration without
// observing a change to the record before it can attempt to take over even
// when a client with a different identity against the record's starts and
// the renew time in the record is older than LeaseDuration. A.k.a., when
// all clients are shutdown and after at least a LeaseDuration, clients
// started with different identities against the record's must wait a full
// LeaseDuration before acquiring a lock. Thus LeaseDuration should be as
// short as possible to avoid a possible long waiting. LeaseDuration is 15
// seconds in core Kubernetes components.
LeaseDuration time.Duration LeaseDuration time.Duration
// RenewDeadline is the duration that the acting master will retry // RenewDeadline is the duration that the acting master will retry
// refreshing leadership before giving up. // refreshing leadership before giving up.